Human small intestinal epithelial cells secrete interleukin-7 and differentially express two different interleukin-7 mRNA Transcripts: implications for extrathymic T-cell differentiation.
The small intestinal epithelium, composed of epithelial cells (EC) and intraepithelial T lymphocytes, is exposed to numerous ingested antigens. Small intestinal EC may act as accessory and/or antigen presenting cells for intestinal T cells, some of which may mature extrathymically and regulate local immunity and tolerance. Since interleukin-7 (IL-7) plays an essential role in T cell maturation and activation, we examined its expression by human small intestinal EC. IL-7 was detected by ELISA in supernatants from 4 of 4 epithelial layer (EpL) cultures. Using RT-PCR, IL-7 mRNA was detected in 4 EpL studied, and two distinct IL-7 transcripts were identified in 3 of the 4. The ratios of the intensities of the larger to the smaller bands varied amongst individuals. Furthermore, the intensity ratios were higher in whole-thickness intestine and lamina propria preparations than in their corresponding EpL. This is the first report of the expression of two IL-7 transcripts in human intestine and of IL-7 secretion by human small intestinal EpL cells. This supports the hypothesis that small intestinal EC may influence differentiation and/or activation of neighboring T cells. The differential expression of the two transcripts may have important implications for immune regulation in the intestinal epithelium.
Madrigal-Estebas
L
L
Education and Research Centre, St. Vincent's Hospital, Dublin, Ireland. madrigal@svherc.ucd.ie
McManus
R
R
Byrne
B
B
Lynch
S
S
Doherty
D G
DG
Kelleher
D
D
O'Donoghue
D P
DP
Feighery
C
C
O'Farrelly
C
C
D001706:Biopsy; D001854:Bone Marrow Cells / Q000276:immunology; D018938:Caco-2 Cells; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D003106:Colon / Q000166:cytology / Q000276:immunology; D004587:Electrophoresis, Agar Gel; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000276:immunology*; D015870:Gene Expression / Q000276:immunology; D006801:Humans; D015851:Interleukin-7 / Q000096:biosynthesis* / Q000235:genetics*; D007421:Intestine, Small / Q000166:cytology / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D014158:Transcription, Genetic
D015851:Interleukin-7; D012333:RNA, Messenger